Computing devices increasingly rely on touch-sensitive display surfaces for user interface features and functionality. Typically, touch sensitive displays use capacitance associated with human skin in order to detect contact by the user at a particular location on the display surface. Users can use their fingers to tap virtual keys, buttons and enter other commands. In many cases, devices that use touch-sensitive screens can dedicate more of the device's ‘real-estate’ to being a display surface, as such devices do not need as many mechanical interfaces such as keys and keyboards. The number of devices with touch-sensitive screens has increased recently, with greater incorporation of such displays in ‘smart phones’, tablets or slate devices, and touch-interactive computer screens.